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kfifo: add record handling functions
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Add kfifo_in_rec() - puts some record data into the FIFO
 Add kfifo_out_rec() - gets some record data from the FIFO
 Add kfifo_from_user_rec() - puts some data from user space into the FIFO
 Add kfifo_to_user_rec() - gets data from the FIFO and write it to user space
 Add kfifo_peek_rec() - gets the size of the next FIFO record field
 Add kfifo_skip_rec() - skip the next fifo out record
 Add kfifo_avail_rec() - determinate the number of bytes available in a record FIFO

Signed-off-by: Stefani Seibold <stefani@seibold.net>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Acked-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Stefani Seibold authored and Linus Torvalds committed Dec 22, 2009
1 parent a121f24 commit 86d4880
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330 changes: 330 additions & 0 deletions include/linux/kfifo.h
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Original file line number Diff line number Diff line change
Expand Up @@ -278,4 +278,334 @@ static inline unsigned int __kfifo_off(struct kfifo *fifo, unsigned int off)
return off & (fifo->size - 1);
}

/**
* __kfifo_peek_n internal helper function for determinate the length of
* the next record in the fifo
*/
static inline unsigned int __kfifo_peek_n(struct kfifo *fifo,
unsigned int recsize)
{
#define __KFIFO_GET(fifo, off, shift) \
((fifo)->buffer[__kfifo_off((fifo), (fifo)->out+(off))] << (shift))

unsigned int l;

l = __KFIFO_GET(fifo, 0, 0);

if (--recsize)
l |= __KFIFO_GET(fifo, 1, 8);

return l;
#undef __KFIFO_GET
}

/**
* __kfifo_poke_n internal helper function for storing the length of
* the next record into the fifo
*/
static inline void __kfifo_poke_n(struct kfifo *fifo,
unsigned int recsize, unsigned int n)
{
#define __KFIFO_PUT(fifo, off, val, shift) \
( \
(fifo)->buffer[__kfifo_off((fifo), (fifo)->in+(off))] = \
(unsigned char)((val) >> (shift)) \
)

__KFIFO_PUT(fifo, 0, n, 0);

if (--recsize)
__KFIFO_PUT(fifo, 1, n, 8);
#undef __KFIFO_PUT
}

/**
* __kfifo_in_... internal functions for put date into the fifo
* do not call it directly, use kfifo_in_rec() instead
*/
extern unsigned int __kfifo_in_n(struct kfifo *fifo,
const void *from, unsigned int n, unsigned int recsize);

extern unsigned int __kfifo_in_generic(struct kfifo *fifo,
const void *from, unsigned int n, unsigned int recsize);

static inline unsigned int __kfifo_in_rec(struct kfifo *fifo,
const void *from, unsigned int n, unsigned int recsize)
{
unsigned int ret;

ret = __kfifo_in_n(fifo, from, n, recsize);

if (likely(ret == 0)) {
if (recsize)
__kfifo_poke_n(fifo, recsize, n);
__kfifo_add_in(fifo, n + recsize);
}
return ret;
}

/**
* kfifo_in_rec - puts some record data into the FIFO
* @fifo: the fifo to be used.
* @from: the data to be added.
* @n: the length of the data to be added.
* @recsize: size of record field
*
* This function copies @n bytes from the @from into the FIFO and returns
* the number of bytes which cannot be copied.
* A returned value greater than the @n value means that the record doesn't
* fit into the buffer.
*
* Note that with only one concurrent reader and one concurrent
* writer, you don't need extra locking to use these functions.
*/
static inline __must_check unsigned int kfifo_in_rec(struct kfifo *fifo,
void *from, unsigned int n, unsigned int recsize)
{
if (!__builtin_constant_p(recsize))
return __kfifo_in_generic(fifo, from, n, recsize);
return __kfifo_in_rec(fifo, from, n, recsize);
}

/**
* __kfifo_out_... internal functions for get date from the fifo
* do not call it directly, use kfifo_out_rec() instead
*/
extern unsigned int __kfifo_out_n(struct kfifo *fifo,
void *to, unsigned int reclen, unsigned int recsize);

extern unsigned int __kfifo_out_generic(struct kfifo *fifo,
void *to, unsigned int n,
unsigned int recsize, unsigned int *total);

static inline unsigned int __kfifo_out_rec(struct kfifo *fifo,
void *to, unsigned int n, unsigned int recsize,
unsigned int *total)
{
unsigned int l;

if (!recsize) {
l = n;
if (total)
*total = l;
} else {
l = __kfifo_peek_n(fifo, recsize);
if (total)
*total = l;
if (n < l)
return l;
}

return __kfifo_out_n(fifo, to, l, recsize);
}

/**
* kfifo_out_rec - gets some record data from the FIFO
* @fifo: the fifo to be used.
* @to: where the data must be copied.
* @n: the size of the destination buffer.
* @recsize: size of record field
* @total: pointer where the total number of to copied bytes should stored
*
* This function copies at most @n bytes from the FIFO to @to and returns the
* number of bytes which cannot be copied.
* A returned value greater than the @n value means that the record doesn't
* fit into the @to buffer.
*
* Note that with only one concurrent reader and one concurrent
* writer, you don't need extra locking to use these functions.
*/
static inline __must_check unsigned int kfifo_out_rec(struct kfifo *fifo,
void *to, unsigned int n, unsigned int recsize,
unsigned int *total)

{
if (!__builtin_constant_p(recsize))
return __kfifo_out_generic(fifo, to, n, recsize, total);
return __kfifo_out_rec(fifo, to, n, recsize, total);
}

/**
* __kfifo_from_user_... internal functions for transfer from user space into
* the fifo. do not call it directly, use kfifo_from_user_rec() instead
*/
extern unsigned int __kfifo_from_user_n(struct kfifo *fifo,
const void __user *from, unsigned int n, unsigned int recsize);

extern unsigned int __kfifo_from_user_generic(struct kfifo *fifo,
const void __user *from, unsigned int n, unsigned int recsize);

static inline unsigned int __kfifo_from_user_rec(struct kfifo *fifo,
const void __user *from, unsigned int n, unsigned int recsize)
{
unsigned int ret;

ret = __kfifo_from_user_n(fifo, from, n, recsize);

if (likely(ret == 0)) {
if (recsize)
__kfifo_poke_n(fifo, recsize, n);
__kfifo_add_in(fifo, n + recsize);
}
return ret;
}

/**
* kfifo_from_user_rec - puts some data from user space into the FIFO
* @fifo: the fifo to be used.
* @from: pointer to the data to be added.
* @n: the length of the data to be added.
* @recsize: size of record field
*
* This function copies @n bytes from the @from into the
* FIFO and returns the number of bytes which cannot be copied.
*
* If the returned value is equal or less the @n value, the copy_from_user()
* functions has failed. Otherwise the record doesn't fit into the buffer.
*
* Note that with only one concurrent reader and one concurrent
* writer, you don't need extra locking to use these functions.
*/
static inline __must_check unsigned int kfifo_from_user_rec(struct kfifo *fifo,
const void __user *from, unsigned int n, unsigned int recsize)
{
if (!__builtin_constant_p(recsize))
return __kfifo_from_user_generic(fifo, from, n, recsize);
return __kfifo_from_user_rec(fifo, from, n, recsize);
}

/**
* __kfifo_to_user_... internal functions for transfer fifo data into user space
* do not call it directly, use kfifo_to_user_rec() instead
*/
extern unsigned int __kfifo_to_user_n(struct kfifo *fifo,
void __user *to, unsigned int n, unsigned int reclen,
unsigned int recsize);

extern unsigned int __kfifo_to_user_generic(struct kfifo *fifo,
void __user *to, unsigned int n, unsigned int recsize,
unsigned int *total);

static inline unsigned int __kfifo_to_user_rec(struct kfifo *fifo,
void __user *to, unsigned int n,
unsigned int recsize, unsigned int *total)
{
unsigned int l;

if (!recsize) {
l = n;
if (total)
*total = l;
} else {
l = __kfifo_peek_n(fifo, recsize);
if (total)
*total = l;
if (n < l)
return l;
}

return __kfifo_to_user_n(fifo, to, n, l, recsize);
}

/**
* kfifo_to_user_rec - gets data from the FIFO and write it to user space
* @fifo: the fifo to be used.
* @to: where the data must be copied.
* @n: the size of the destination buffer.
* @recsize: size of record field
* @total: pointer where the total number of to copied bytes should stored
*
* This function copies at most @n bytes from the FIFO to the @to.
* In case of an error, the function returns the number of bytes which cannot
* be copied.
* If the returned value is equal or less the @n value, the copy_to_user()
* functions has failed. Otherwise the record doesn't fit into the @to buffer.
*
* Note that with only one concurrent reader and one concurrent
* writer, you don't need extra locking to use these functions.
*/
static inline __must_check unsigned int kfifo_to_user_rec(struct kfifo *fifo,
void __user *to, unsigned int n, unsigned int recsize,
unsigned int *total)
{
if (!__builtin_constant_p(recsize))
return __kfifo_to_user_generic(fifo, to, n, recsize, total);
return __kfifo_to_user_rec(fifo, to, n, recsize, total);
}

/**
* __kfifo_peek_... internal functions for peek into the next fifo record
* do not call it directly, use kfifo_peek_rec() instead
*/
extern unsigned int __kfifo_peek_generic(struct kfifo *fifo,
unsigned int recsize);

/**
* kfifo_peek_rec - gets the size of the next FIFO record data
* @fifo: the fifo to be used.
* @recsize: size of record field
*
* This function returns the size of the next FIFO record in number of bytes
*/
static inline __must_check unsigned int kfifo_peek_rec(struct kfifo *fifo,
unsigned int recsize)
{
if (!__builtin_constant_p(recsize))
return __kfifo_peek_generic(fifo, recsize);
if (!recsize)
return kfifo_len(fifo);
return __kfifo_peek_n(fifo, recsize);
}

/**
* __kfifo_skip_... internal functions for skip the next fifo record
* do not call it directly, use kfifo_skip_rec() instead
*/
extern void __kfifo_skip_generic(struct kfifo *fifo, unsigned int recsize);

static inline void __kfifo_skip_rec(struct kfifo *fifo,
unsigned int recsize)
{
unsigned int l;

if (recsize) {
l = __kfifo_peek_n(fifo, recsize);

if (l + recsize <= kfifo_len(fifo)) {
__kfifo_add_out(fifo, l + recsize);
return;
}
}
kfifo_reset_out(fifo);
}

/**
* kfifo_skip_rec - skip the next fifo out record
* @fifo: the fifo to be used.
* @recsize: size of record field
*
* This function skips the next FIFO record
*/
static inline void kfifo_skip_rec(struct kfifo *fifo,
unsigned int recsize)
{
if (!__builtin_constant_p(recsize))
__kfifo_skip_generic(fifo, recsize);
else
__kfifo_skip_rec(fifo, recsize);
}

/**
* kfifo_avail_rec - returns the number of bytes available in a record FIFO
* @fifo: the fifo to be used.
* @recsize: size of record field
*/
static inline __must_check unsigned int kfifo_avail_rec(struct kfifo *fifo,
unsigned int recsize)
{
unsigned int l = kfifo_size(fifo) - kfifo_len(fifo);

return (l > recsize) ? l - recsize : 0;
}

#endif
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